Rubber composition comprising a polyphenylene ether resin as plasticizer

ABSTRACT

A rubber composition is based on at least one predominant vinylaromatic diene elastomer, a reinforcing filler, a crosslinking system and a thermoplastic resin comprising optionally substituted polyphenylene ether units, said resin having a number-average molecular weight (Mn) of less than 6000 g/mol. The rubber composition can be used in semi-finished tire articles and tires.

The present invention relates to rubber compositions, especiallyintended for the manufacture of tyres or semi-finished products fortyres, in particular rubber compositions for tyre treads having a greatease of manufacture of the mixtures and good wear resistance of thetyre.

Tyres are subjected to numerous stresses during the use thereof. Tyretreads especially must respond to a large number of often conflictingtechnical requirements, including high wear resistance and good dry andwet grip. The mixtures for these tyres must also have goodprocessability, that is to say they must be easy to manufacture.

It is known practice to use elastomers combined with reinforcing fillersand plasticizing agents in tyre compositions. Conventionally, theseplasticizing agents may be plasticizing oils or plasticizing resins,such as described in numerous documents, for example in patentapplications FR 2 866 028, FR 2 877 348 or FR 2 889 538, describingespecially the use of thermoplastic resins as plasticizing resins.

Moreover, Japanese document JP 2004-238547 describes a compositioncomprising micrometre-sized particles (approximately 10 μm or 45 μm) ofa polyphenylene ether resin which make it possible to increase thestiffness of the compositions, with an increase in the hysteresis of thecompositions which is deemed acceptable. In this document, thepolyphenylene ether resin is used in the form of micrometric particles(approximately 10 μm or 45 μm) and not in the form of a compatibleplasticizer, dispersed and intimately mixed with the elastomer matrix ofthe composition.

At present, the applicants have discovered during their research that athermoplastic resin based on optionally substituted polyphenylene etherunits may advantageously be used as plasticizing resin in a compositionin which the predominant elastomer is a vinylaromatic diene elastomer.The use of a plasticizing resin makes it possible surprisingly toimprove the performance compromise between ease of manufacturing themixtures, and tyre grip. Moreover, the use of these thermoplastic resinsbased on optionally substituted polyphenylene ether units makes itpossible to reduce the amount of resin compared to conventionalthermoplastic plasticizing resins, which makes possible a reduction inthe green tack of the compositions which is linked to the use of theseresins, and therefore facilitates the manufacture of tyres comprisingthese compositions.

Consequently, a first subject of the invention relates to a rubbercomposition based on at least one predominant vinylaromatic dieneelastomer, a reinforcing filler, a crosslinking system and athermoplastic resin comprising optionally substituted polyphenyleneether units, said resin having a number-average molecular weight (Mn) ofless than 6000 g/mol.

Preferably, the invention relates to a composition as defined above, inwhich said resin has a number-average molecular weight (Mn) of less than3500 g/mol, more preferably within a range extending from 700 to 2500g/mol.

Preferably, the invention relates to a composition as defined above, inwhich the vinylaromatic diene elastomer has a vinylaromatic content ofgreater than 10%, preferably of between 15% and 60%, more preferablybetween 20% and 50%, very preferably between 30% and 50% and even morepreferably between 35% and 50%.

Alternatively and also preferably, the invention relates to acomposition as defined above, in which the vinylaromatic diene elastomerhas a vinylaromatic content of between 10% and 30%, and in which saidresin has a number-average molecular weight (Mn) of less than 2200g/mol. More preferably, the vinylaromatic diene elastomer has avinylaromatic content of between 12% and 28%, and said resin has anumber-average molecular weight (Mn) of less than 2000 g/mol. Morepreferably still, the vinylaromatic diene elastomer has a vinylaromaticcontent of between 14% and 20%, and said resin has a number-averagemolecular weight (Mn) within a range extending from 700 to 2000 g/mol.

Preferably, the vinylaromatic diene elastomer is selected from the groupconsisting of butadiene/styrene copolymers, isoprene/styrene copolymersand butadiene/isoprene/styrene copolymers and mixtures of theseelastomers, and preferably from the group consisting ofbutadiene/styrene copolymers and mixtures of the latter. Alsopreferably, the content of vinylaromatic diene elastomer is within arange extending from 70 to 100 phr (parts by weight per hundred parts ofelastomer) and more preferably from 85 to 100 phr.

Preferably, the invention relates to a composition as defined above, inwhich the thermoplastic resin based on optionally substitutedpolyphenylene ether units has a glass transition temperature (Tg),measured by DSC according to standard ASTM D3418, 1999, within a rangeextending from 0 to 215° C., preferably from 5 to 200° C. and morepreferably from 5 to 185° C.

Preferably, the invention relates to a composition as defined above, inwhich the thermoplastic resin based on optionally substitutedpolyphenylene ether units is a compound which predominantly comprisespolyphenylene units of general formula (I):

in which:

R₁, R₂, R₃ and R₄ represent, independently of one another, identical ordifferent groups selected from hydrogen, hydroxyl, alkoxy, halogen,amino, alkylamino or dialkylamino groups or hydrocarbon-based groupscomprising at least 2 carbon atoms, optionally interrupted byheteroatoms and optionally substituted; R₁ and R₃ on the one hand, andR₂ and R₄ on the other hand, possibly forming, together with the carbonatoms to which they are attached, one or more rings fused to the benzenering of the compound of formula (I),

n is an integer within a range extending from 3 to 300.

Preferably, the invention relates to a composition as defined above, inwhich the thermoplastic resin based on optionally substitutedpolyphenylene ether units is a compound predominantly comprisingpolyphenylene units of general formula (I) in which R₁, R₂, R₃ and R₄represent, independently of one another, identical or different groupsselected from:

hydrogen,

hydroxyl, alkoxy, halogen, amino, alkylamino or dialkylamino groups,

linear, branched or cyclic alkyl groups, comprising from 1 to 25 carbonatoms (preferably from 2 to 18), optionally interrupted by heteroatomsselected from nitrogen, oxygen and sulphur and optionally substituted byhydroxyl, alkoxy, amino, alkylamino, dialkylamino or halogen groups,

aryl groups comprising from 6 to 18 carbon atoms (preferably from 6 to12), optionally substituted by hydroxyl, alkoxy, amino, alkylamino,dialkylamino, alkyl or halogen groups.

Preferably, the invention relates to a composition as defined above, inwhich the thermoplastic resin based on optionally substitutedpolyphenylene ether units is a compound predominantly comprisingpolyphenylene units of general formula (I) in which R₁, R₂, R₃ and R₄represent, independently of one another, identical or different groupsselected from:

hydrogen,

hydroxyl, alkoxy comprising from 1 to 6 carbon atoms, halogen, amino,alkylamino comprising from 1 to 6 carbon atoms, or dialkylaminocomprising from 2 to 12 carbon atoms groups,

linear, branched or cyclic alkyl groups, comprising from 1 to 12 carbonatoms (preferably from 2 to 6), optionally interrupted by heteroatomsand optionally substituted by hydroxyl, alkoxy comprising from 1 to 6carbon atoms, amino, alkylamino comprising from 1 to 6 carbon atoms,dialkylamino comprising from 2 to 12 carbon atoms, or halogen groups,

aryl groups comprising from 6 to 18 carbon atoms (preferably from 6 to12), optionally substituted by hydroxyl, alkoxy comprising from 1 to 6atoms, amino, alkylamino comprising from 1 to 6 atoms, dialkylaminocomprising from 2 to 12 carbon atoms, alkyl comprising from 1 to 12carbon atoms, or halogen groups.

Preferably, the invention relates to a composition as defined above, inwhich R₁ and R₂ represent an alkyl group and in particular a methylgroup, and R₃ and R₄ represent hydrogen atoms.

More preferably, the invention relates to a composition as definedabove, in which the thermoplastic resin based on optionally substitutedpolyphenylene ether units is a compound which predominantly comprisespolyphenylene units of general formula (I) in which n is an integerwithin a range extending from 3 to 50, preferably from 5 to 30 and morepreferably from 6 to 20.

Preferably, the invention relates to a composition as defined above, inwhich the thermoplastic resin based on optionally substitutedpolyphenylene ether units is a compound which comprises more than 80% byweight, preferably more than 95% by weight, of polyphenylene units ofgeneral formula (I).

Preferably, the invention relates to a composition as defined above, inwhich the content of said thermoplastic resin based on optionallysubstituted polyphenylene ether units is within a range extending from 1to 90 phr, preferably from 2 to 80 phr, more preferably from 3 to 60 phrand better still from 5 to 60 phr.

Preferably, the invention relates to a composition as defined above, inwhich the reinforcing filler comprises carbon black and/or silica.

Also preferably, the invention relates to a composition as definedabove, in which the reinforcing filler represents between 20 and 250phr, more preferably between 30 and 180 phr.

Preferably, the invention relates to a composition as defined above, inwhich the reinforcing filler predominantly comprises carbon black.Preferably, the carbon black represents from 40 to 150 phr, preferablyfrom 50 to 120 phr.

Alternatively and also preferably, the invention relates to acomposition as defined above, in which the reinforcing fillerpredominantly comprises silica. Preferably, the silica represents from40 to 150 phr, preferably from 50 to 120 phr.

Another subject of the invention is finished or semi-finished rubberarticles comprising a rubber composition in accordance with theinvention.

Another subject of the invention is tyres comprising a rubbercomposition in accordance with the invention, and especially tyres inwhich the tread comprises a rubber composition according to theinvention.

The tyres in accordance with the invention are especially intended forpassenger vehicles as well as for two-wheel vehicles (motorcycles,bicycles), industrial vehicles chosen from vans, “heavy-duty”vehicles—i.e. underground, bus, heavy road transport vehicles (lorries,tractors, trailers), off-road vehicles, heavy agricultural vehicles orearthmoving equipment, aircraft, and other transportation or handlingvehicles.

The invention and its advantages will be readily understood in the lightof the description and the exemplary embodiments that follow.

I. TESTS

The rubber compositions are characterized, before and after curing, asindicated below.

I.1. Dynamic Properties after Curing

The dynamic properties G* are measured on a viscosity analyser (MetravibVA4000) according to standard ASTM D 5992-96. The response is recordedof a sample of vulcanized composition (that is to say cured until aconversion rate of at least 90% is achieved) (cylindrical test specimenwith a thickness of 2 mm and a cross section of 78.5 mm²), subjected toa simple alternating sinusoidal shear stress, at a frequency of 10 Hz.

A temperature sweep is carried out at a constant temperature rise rateof +1.5° C./min with an imposed peak-to-peak shear stress of 0.7 MPa.The test specimen is subjected to sinusoidal shear stress at 10 Hzsymmetrically about its equilibrium position. The results utilized arethe complex dynamic shear modulus (G*), and the viscous component of theshear modulus (G″), denoted G″(T).

The glass transition temperature (denoted Tg) according to the inventioncorresponds to the temperature at which the maximum observed G″ isobserved during the temperature sweep. Thus, in the present description,unless expressly indicated otherwise, Tg is defined as the temperatureat which the maximum G″ is observed (G″ representing, in a known way,the viscous component of the shear modulus) during the temperature sweepof a crosslinked sample subjected to imposed sinusoidal stress of 0.7MPa at a frequency of 10 Hz. As indicated above, this Tg is measuredduring the measurement of dynamic properties, on a viscosity analyser(Metravib VA4000) according to standard ASTM D 5992-96. The sample forthis measurement of Tg is crosslinked with sulphur at a content ofapproximately 1.5 phr and with N-cyclohexylbenzothiazolesulphenamide(CBS) at a content of approximately 2 phr.

I.2. Rheometry

The measurements are carried out at 150° C. with an oscillating discrheometer, according to standard DIN 53529—part 3 (June 1983). Thechange in the rheometric torque, Δtorque, as a function of timedescribes the change in the stiffening of the composition as a result ofthe vulcanization reaction. The measurements are processed according tostandard DIN 53529—Part 2 (March 1983): To is the induction period, thatis to say the time necessary for the start of the vulcanizationreaction; Tα (for example T99) is the time necessary to achieve aconversion of α %, that is to say α % (for example 99%) of thedifference between the minimum and maximum torques. The conversion rateconstant, denoted K (expressed in min⁻¹), which is first order,calculated between 30% and 80% conversion, which makes it possible toassess the vulcanization kinetics, is also measured.

I.3. Measurement of Particle Content

The measurements are carried out on a transmission optical microscope(TOM) on an Olympus device with reference BX-51. The observations arecarried out in “bright field” mode with “40 times” magnification(objective lens×40−additional magnification×1−camera ringmagnification×1). The images are obtained in black and white by anOlympus DP-50 capturing camera. For this magnification, the field ofobservation corresponding to an image is 160 μm×120 μm. In order tocover a significant surface area, the measurements of particle surfacecontent are carried out on at least 10 images. The samples observed areobtained using a cryomicrotome at −60° C. with a guideline cutting sizeof 2 μm.

Within the context of the present application, when reference is made tothe compatibility of the PPE resin and the predominant vinylaromaticdiene elastomer, “compatible” is intended to mean that this PPE resindoes not form particles in the composition, that is to say that, in amixture of the PPE resin and the vinylaromatic diene elastomer, acomposition having less than 10% of its volume in the form of particlesgreater than 2 micrometres (μm) in size will be observed. Morepreferably, in a mixture of the PPE resin and the vinylaromatic dieneelastomer, a composition having less than 5%, and preferably less than2%, of its volume in the form of particles greater than 2 micrometres(μm) in size will be observed. This observation of particle content andsize of particles may be carried out using the TOM as described above.

A composition in which less than 10% of said resin is in the form ofparticles greater than 2 micrometres in size corresponds to acomposition in which, if 10 contiguous images are observed on 2 μmsections under the TOM as described above, on average less than 10% ofthe observed surface corresponding to particles greater than 2 μm insize will be found.

II. CONDITIONS FOR THE IMPLEMENTATION OF THE INVENTION

The rubber composition according to the invention is based on at leastone predominant vinylaromatic diene elastomer, a reinforcing filler, acrosslinking system and a thermoplastic resin comprising optionallysubstituted polyphenylene ether units, said resin having anumber-average molecular weight (Mn) of less than 6000 g/mol.

The expression composition “based on” should be understood as meaning acomposition comprising the mixture and/or the reaction product of thevarious constituents used, some of these base constituents being capableof reacting or intended to react with one another, at least in part,during the various phases of manufacturing the composition, inparticular during the crosslinking or vulcanization thereof.

In the present description, unless expressly indicated otherwise, allthe percentages (%) shown are percentages (%) by weight. Furthermore,any interval of values denoted by the expression “between a and b”represents the range of values extending from more than a to less than b(that is to say, limits a and b excluded), whereas any interval ofvalues denoted by the expression “from a to b” means the range of valuesextending from a up to b (that is to say, including the strict limits aand b).

When reference is made to a “predominant” compound, this is understoodto mean, within the meaning of the present invention, that this compoundis predominant among the compounds of the same type in the composition,that is to say that it is the one which represents the greatest amountby weight among the compounds of the same type. Thus, for example, apredominant elastomer is the elastomer representing the greatest weightwith respect to the total weight of the elastomers in the composition.In the same way, a “predominant” filler is that representing thegreatest weight among the fillers of the composition. By way of example,in a system comprising just one elastomer, the latter is predominantwithin the meaning of the present invention and, in a system comprisingtwo elastomers, the predominant elastomer represents more than half ofthe weight of the elastomers.

II.1. Elastomers

The rubber composition according to the invention comprises apredominant vinylaromatic diene elastomer.

The term “diene” elastomer or rubber should be understood, in a knownway, as meaning an (one or more is understood) elastomer resulting atleast in part (i.e., a homopolymer or a copolymer) from diene monomers(monomers bearing two conjugated or non-conjugated carbon-carbon doublebonds).

These definitions being given, the term “vinylaromatic diene elastomer”more particularly means any copolymer obtained by copolymerization ofone or more conjugated dienes with one another or with one or morevinylaromatic compounds having from 8 to 20 carbon atoms.

The following are suitable in particular as conjugated dienes:1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di(C₁-C₅alkyl)-1,3-butadienes, such as, for example, 2,3-dimethyl-1,3-butadiene,2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene,2-methyl-3-isopropyl-1,3-butadiene, aryl-1,3-butadiene, 1,3-pentadieneor 2,4-hexadiene.

The following, for example, are suitable as vinylaromatic compounds:styrene, α-methylstyrene, ortho-, meta- or para-methylstyrene, the“vinyltoluene” commercial mixture, para-(tert-butyl)styrene,methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene orvinylnaphthalene.

The copolymers may contain between 99% and 20% by weight of diene unitsand between 1% and 80% by weight of vinylaromatic units. The elastomersmay have any microstructure, which depends on the polymerizationconditions used, especially on the presence or absence of a modifyingand/or randomizing agent and on the amounts of modifying and/orrandomizing agent employed. The elastomers may, for example, be block,statistical, sequential or microsequential elastomers and may beprepared in dispersion or in solution; they may be coupled and/orstar-branched or else functionalized with a coupling and/orstar-branching or functionalization agent. Mention may be made, forexample, for coupling to carbon black, of functional groups comprising aC—Sn bond or aminated functional groups, such as benzophenone, forexample; mention may be made, for example, for coupling to a reinforcinginorganic filler, such as silica, of silanol functional groups orpolysiloxane functional groups having a silanol end (such as described,for example, in FR 2 740 778 or U.S. Pat. No. 6,013,718), alkoxysilanegroups (such as described, for example, in FR 2 765 882 or U.S. Pat. No.5,977,238), carboxyl groups (such as described, for example, in WO01/92402 or U.S. Pat. No. 6,815,473, WO 2004/096865 or US 2006/0089445)or else polyether groups (such as described, for example, in EP 1 127909 or U.S. Pat. No. 6,503,973). Mention may also be made, as otherexamples of functionalized elastomers, of vinylaromatic diene elastomers(such as SBR) of the epoxidized type.

Preferably, the vinylaromatic diene elastomer of the composition inaccordance with the invention has a vinylaromatic content of greaterthan 10%, preferably of between 15% and 60%, more preferably between 20%and 50%, very preferably between 30% and 50% and even more preferablybetween 35% and 50%. More preferably, the vinylaromatic diene elastomerof the composition in accordance with the invention is a styrene dieneelastomer (that is to say that the vinylaromatic part is a styrene part)with a styrene content of greater than 10%, preferably of between 15%and 50%, more preferably between 20% and 50%, very preferably between30% and 50% and even more preferably between 35% and 50%.

Alternatively and also preferably, the vinylaromatic diene elastomer ofthe composition in accordance with the invention has a vinylaromaticcontent of between 10% and 30%, preferably between 12% and 28% and morepreferably between 14% and 20%. More preferably, the vinylaromatic dieneelastomer of the composition in accordance with the invention is astyrene diene elastomer (that is to say that the vinylaromatic part is astyrene part) with a styrene content of between 10% and 30%, preferablybetween 12% and 28% and more preferably between 14% and 20%.

Preferably, the vinylaromatic diene elastomer of the composition inaccordance with the invention is selected with preference from the groupof highly unsaturated styrene diene elastomers consisting of styrenecopolymers of butadiene, styrene copolymers of isoprene and mixtures ofthese elastomers. Such copolymers are more preferably selected from thegroup consisting of butadiene/styrene copolymers (SBR), isoprene/styrenecopolymers (SIR) and isoprene/butadiene/styrene copolymers (SBIR).

The following are especially suitable: butadiene/styrene copolymers(SBR) and in particular those with a Tg (glass transition temperature),measured by DSC according to standard ASTM D3418, 1999, of between 20°C. and −70° C. and more particularly between 0° C. and −50° C., astyrene content of between 10% and 60% by weight and more particularlybetween 20% and 50%, a content (mol %) of −1,2 bonds in the butadienepart of between 4% and 75%, and a content (mol %) of trans-1,4 bonds ofbetween 10% and 80%.

The following are also suitable: isoprene/styrene copolymers (SIR) andespecially those having a styrene content of between 15% and 60% byweight and more particularly between 20% and 50%, and a Tg, measured byDSC according to standard ASTM D3418, 1999, of between 25° C. and −50°C.

In the case of butadiene/styrene/isoprene copolymers (SBIR), thosehaving a styrene content of between 15% and 60% by weight and moreparticularly of between 20% and 50%, an isoprene content of between 15%and 60% by weight and more particularly between 20% and 50%, a butadienecontent of between 5% and 50% by weight and more particularly of between20% and 40%, a content (mol %) of 1,2-units of the butadiene part ofbetween 4% and 85%, a content (mol %) of trans-1,4-units of thebutadiene part of between 6% and 80%, a content (mol %) of 1,2-plus3,4-units of the isoprene part of between 5% and 70% and a content (mol%) of trans-1,4-units of the isoprene part of between 10% and 50%, andmore generally any butadiene/styrene/isoprene copolymer having a Tg,measured by DSC according to standard ASTM D3418, 1999, of between 20°C. and −60° C., are especially suitable.

Very preferably, the vinylaromatic diene elastomer of the composition inaccordance with the invention is an SBR. In a known way, SBR may beprepared as emulsion (ESBR) or prepared as solution (SSBR). In the caseof an SBR elastomer (ESBR or SSBR), an SBR having an average styrenecontent, for example of between 25% and 50% by weight, preferablybetween 35% and 50% by weight, is especially used.

The compositions of the invention may contain a single vinylaromaticdiene elastomer or a mixture of several vinylaromatic diene elastomers,with the vinylaromatic diene elastomers(s), always predominant, beingable to be used in combination with other elastomers known to thoseskilled in the art, such as for example a natural rubber (NR) or apolybutadiene (BR).

The content of vinylaromatic diene elastomer is within a range extendingfrom 70 to 100 phr, more preferably from 85 to 100 phr, and verypreferably this content is 100 phr, that is to say that there are onlyvinylaromatic diene elastomers in the composition.

II.2. Reinforcing Filler

Use may be made of any type of reinforcing filler known for itsabilities to reinforce a rubber composition which can be used for themanufacture of tyres, for example an organic filler, such as carbonblack, a reinforcing inorganic filler, such as silica, or else a blendof these two types of filler, in particular a blend of carbon black andsilica.

All carbon blacks, especially blacks of the HAF, ISAF, SAF type,conventionally used in tyres (blacks referred to as tyre grade blacks)are suitable as carbon black. Mention will more particularly be made,among the latter, of the reinforcing carbon blacks of the 100, 200 or300 series (ASTM grades), such as, for example, the N115,

N134, N234, N326, N330, N339, N347 or N375 blacks, or else, according tothe intended applications, the blacks of higher series (for exampleN660, N683, N772). The carbon blacks might, for example, be alreadyincorporated in an isoprene elastomer in the form of a masterbatch (see,for example, application WO 97/36724 or WO 99/16600).

Mention may be made, as examples of organic fillers other than carbonblacks, of functionalized polyvinyl organic fillers, such as describedin applications WO-A-2006/069792, WO-A-2006/069793, WO-A-2008/003434 andWO-A-2008/003435.

“Reinforcing inorganic filler” should be understood, in the presentapplication, by definition, as meaning any inorganic or mineral filler,(irrespective of its colour and its origin: natural or synthetic), alsoknown as “white filler”, “clear filler” or indeed even “non-blackfiller”, in contrast to carbon black, capable of reinforcing by itselfalone, without means other than an intermediate coupling agent, a rubbercomposition intended for the manufacture of tyres, in other wordscapable of replacing, in its reinforcing role, a conventional tyre-gradecarbon black; such a filler is generally characterized, in a known way,by the presence of hydroxyl (—OH) groups at its surface.

The physical state in which the reinforcing inorganic filler is providedis not important, whether it is in the form of a powder, of micropearls,of granules, of beads or any other appropriate densified form. Ofcourse, reinforcing inorganic filler is also intended to mean mixturesof different reinforcing inorganic fillers, in particular of highlydispersible siliceous and/or aluminous fillers as described below.

Mineral fillers of the siliceous type, in particular silica (SiO₂), orof the aluminous type, in particular alumina (Al₂O₃), are suitable inparticular as reinforcing inorganic fillers. The silica used can be anyreinforcing silica known to a person skilled in the art, in particularany precipitated or fumed silica having a BET surface area and a CTABspecific surface area both of less than 450 m²/g, preferably from 30 to400 m²/g. Mention will be made, as highly dispersible precipitatedsilicas (“HDSs”), for example, of the Ultrasil 7000 and Ultrasil 7005silicas from Degussa, the Zeosil 1165MP, 1135MP and 1115MP silicas fromRhodia, the Hi-Sil EZ150G silica from PPG, the Zeopol 8715, 8745 and8755 silicas from Huber or the silicas with a high specific surface areaas described in application WO 03/16837.

The reinforcing inorganic filler used, in particular if it is silica,preferably has a BET surface area of between 45 and 400 m²/g, morepreferably of between 60 and 300 m²/g.

Preferably, the content of total reinforcing filler (carbon black and/orreinforcing inorganic filler, such as silica) is between 20 and 200 phr,more preferably between 30 and 160 phr, the optimum being, in a knownway, different depending on the specific applications targeted: thelevel of reinforcement expected for a bicycle tyre, for example, is, ofcourse, less than that required for a tyre capable of running at highspeed in a sustained manner, for example a motorcycle tyre, a tyre for apassenger vehicle or a tyre for a utility vehicle, such as a heavy-dutyvehicle.

According to a first preferred embodiment of the invention, carbon blackis used as predominant reinforcing filler, at between 60 and 160 phr andmore preferably between 70 and 150 phr.

According to another preferred embodiment of the invention, use is madeof silica as predominant reinforcing filler at between 60 and 160 phr,more preferably between 70 and 150 phr, and optionally of carbon black;the carbon black, when it is present, is preferably used at a content ofless than 20 phr, more preferably of less than 10 phr (for examplebetween 0.1 and 5 phr).

In order to couple the reinforcing inorganic filler to the dieneelastomer, use is made, in a known manner, of an at least bifunctionalcoupling agent (or bonding agent) intended to provide a satisfactoryconnection, of chemical and/or physical nature, between the inorganicfiller (surface of its particles) and the diene elastomer, in particularbifunctional organosilanes or polyorganosiloxanes.

Use is especially made of silane polysulphides, referred to as“symmetrical” or “asymmetrical” depending on their particular structure,as described for example in applications WO 03/002648 (or US2005/016651) and WO 03/002649 (or US 2005/016650).

In particular, without the definition below being limiting, silanepolysulphides referred to as “symmetrical”, corresponding to thefollowing general formula (II), are suitable:

Z-A-Sx-A-Z, in which:

x is an integer from 2 to 8 (preferably from 2 to 5);

A is a divalent hydrocarbon-based radical (preferably C₁-C₁₈ alkylenegroups or C₆-C₁₂ arylene groups, more particularly C₁-C₁₀ alkylenes,especially C₁-C₄ alkylenes, in particular propylene);

Z corresponds to one of the formulae below:

in which:

-   -   the R¹ radicals, which are substituted or unsubstituted and        identical to or different from one another, represent a C₁-C₁₈        alkyl, C₅-C₁₈ cycloalkyl or C₆-C₁₈ aryl group (preferably C₁-C₆        alkyl, cyclohexyl or phenyl groups, especially C₁-C₄ alkyl        groups, more particularly methyl and/or ethyl).    -   the R² radicals, which are substituted or unsubstituted and        identical to or different from one another, represent a C₁-C₁₈        alkoxy or C₅-C₁₈ cycloalkoxy group (preferably a group chosen        from C₁-C₈ alkoxys and C₅-C₈ cycloalkoxys, more preferably still        a group chosen from C₁-C₄ alkoxys, in particular methoxy and        ethoxy).

In the case of a mixture of alkoxysilane polysulphides corresponding tothe above formula, especially customary commercially available mixtures,the mean value of the “x” indices is a fractional number preferably ofbetween 2 and 5, more preferably close to 4. However, the invention mayalso advantageously be carried out, for example, with alkoxysilanedisulphides (x=2).

Mention will more particularly be made, as examples of silanepolysulphides, of bis((C₁-C₄)alkoxy(C₁-C₄)alkylsilyl(C₁-C₄)alkyl)polysulphides (in particular disulphides, trisulphides ortetrasulphides), such as, for example, bis(3-trimethoxysilylpropyl) orbis(3-triethoxysilylpropyl) polysulphides. Use is made in particular,among these compounds, of bis(3-triethoxysilylpropyl) tetrasulphide,abbreviated to TESPT, of formula [(C₂H₅O)₃Si(CH₂)₃S₂]₂, orbis(triethoxysilylpropyl) disulphide, abbreviated to TESPD, of formula[(C₂H₅O)₃Si(CH₂)₃S]₂. Mention will also be made, as preferred examples,of bis(mono(C₁-C₄)alkoxydi(C₁-C₄)alkylsilylpropyl) polysulphides (inparticular disulphides, trisulphides or tetrasulphides), moreparticularly bis(monoethoxydimethylsilylpropyl) tetrasulphide, such asdescribed in patent application WO 02/083782 (or US 2004/132880).

Mention will in particular be made, as coupling agent other thanalkoxysilane polysulphide, of bifunctional POSs (polyorganosiloxanes),or else of hydroxysilane polysulphides (R²═OH in the above formula),such as described in patent applications WO 02/30939 (or U.S. Pat. No.6,774,255) and WO 02/31041 (or US 2004/051210), or else of silanes orPOSs bearing azodicarbonyl functional groups, such as described, forexample, in patent applications WO 2006/125532, WO 2006/125533 and WO2006/125534.

In the rubber compositions in accordance with the invention, the contentof coupling agent is preferably between 4 and 16 phr, more preferablybetween 5 and 15 phr.

Those skilled in the art will understand that, as filler equivalent tothe reinforcing inorganic filler described in the present section, areinforcing filler of another nature, in particular organic nature,could be used provided that this reinforcing filler is covered with aninorganic layer, such as silica, or else comprises functional sites, inparticular hydroxyl sites, at its surface that require the use of acoupling agent in order to form the bond between the filler and theelastomer.

II.3. PPE Resin

The composition according to the invention comprises a thermoplasticresin based on optionally substituted polyphenylene ether units(abbreviated to “PPE resin”). This type of compound is described forexample in the encyclopaedia “Ullmann's Encyclopedia of IndustrialChemistry” published by VCH, vol. A 21, pages 605-614, 5^(th) edition,1992.

In a known way, PPE resins usually have number-average molecular weights(Mn) which are variable, most often from 15 000 to 30 000 g/mol; in thecase of high weights such as these, Mn is measured in a way known tothose skilled in the art by SEC (also referred to as GPC, as inreference U.S. Pat. No. 4,588,806, column 8).

For the purposes of the invention, a PPE resin is used for thecomposition of the invention which has an Mn weight which is lower thanthe weights usually encountered and especially lower than 6000 g/mol,preferably lower than 3500 g/mol and in particular an Mn within a rangeextending from 700 to 2500 g/mol; these preferences apply to allvinylaromatic diene elastomers which may be used according to theinvention, and in particular to those having a vinylaromatic content ofbetween 20% and 50%, very preferably between 30% and 50% and even morepreferably between 35% and 50%. The number-average molecular weight (Mn)of the PPEs with a weight lower than 6000 g/mol is measured by NMR,since the conventional SEC measurement is not precise enough. This NMRmeasurement is carried out in a way known to those skilled in the art,either by assaying the chain end functions or by assaying thepolymerization initiators, as explained for example in “Application ofNMR spectroscopy in molecular weight determination of polymers” bySubhash C. Shit and Sukumar Maiti in “European Polymer Journal” vol. 22,no. 12, pages 1001 to 1008 (1986).

According to a particularly preferred embodiment of the invention, whenthe vinylaromatic diene elastomer has a vinylaromatic content of between10% and 30%, preferably of between 12% and 28%, more preferably between14% and 20%, a PPE resin having a weight Mn lower than the weightsusually encountered and especially lower than 2200 g/mol, preferablylower than 2000 g/mol and in particular an Mn within a range extendingfrom 700 to 2000 g/mol is preferred for the composition of theinvention.

Preferably, the value of the polydispersity index PDI (reminder:PDI=Mw/Mn, with Mw the weight-average molecular weight and Mn thenumber-average molecular weight) of the PPE resin is less than or equalto 5, more preferably less than or equal to 3 and more preferably stillless than or equal to 2.

The PPE resin which is useful for the purposes of the inventionpreferably has a glass transition temperature (Tg), measured by DSCaccording to standard ASTM D3418, 1999, within a range extending from 0to 215° C., preferably from 5 to 200° C. and more preferably from 5 to185° C. Below 0° C. the PPE resin does not enable a sufficient shift ofthe Tg in the composition which comprises it and above 215° C.manufacturing problems, especially in terms of obtaining a homogeneousmixture, may be encountered.

Preferably, the PPE resin is a compound which predominantly comprisespolyphenylene units of general formula (I):

in which:

R₁, R₂, R₃ and R₄ represent, independently of one another, identical ordifferent groups selected from hydrogen; hydroxyl, alkoxy, halogen,amino, alkylamino or dialkylamino groups; hydrocarbon-based groupscomprising at least 2 carbon atoms, optionally interrupted byheteroatoms and optionally substituted; R₁ and R₃ on the one hand, andR₂ and R₄ on the other hand, possibly forming, together with the carbonatoms to which they are attached, one or more rings fused to the benzenering of the compound of formula (I),

n is an integer within a range extending from 3 to 300.

Preferably, R₁, R₂, R₃ and R₄ represent, independently of one another,identical or different groups selected from:

hydrogen,

hydroxyl, alkoxy, halogen, amino, alkylamino or dialkylamino groups,

linear, branched or cyclic alkyl groups, comprising from 1 to 25 carbonatoms (preferably from 2 to 18), optionally interrupted by heteroatomsselected from nitrogen, oxygen and sulphur and optionally substituted byhydroxyl, alkoxy, amino, alkylamino, dialkylamino or halogen groups,

aryl groups comprising from 6 to 18 carbon atoms (preferably from 6 to12), optionally substituted by hydroxyl, alkoxy, amino, alkylamino,dialkylamino, alkyl or halogen groups.

More preferably, R₁, R₂, R₃ and R₄ represent, independently of oneanother, identical or different groups selected from:

hydrogen,

hydroxyl, alkoxy comprising from 1 to 6 carbon atoms, halogen, amino,alkylamino comprising from 1 to 6 carbon atoms, or dialkylaminocomprising from 2 to 12 carbon atoms groups,

linear, branched or cyclic alkyl groups, comprising from 1 to 12 carbonatoms (preferably from 2 to 6), optionally interrupted by heteroatomsand optionally substituted by hydroxyl, alkoxy comprising from 1 to 6carbon atoms, amino, alkylamino comprising from 1 to 6 carbon atoms,dialkylamino comprising from 2 to 12 carbon atoms, or halogen groups,

aryl groups comprising from 6 to 18 carbon atoms (preferably from 6 to12), optionally substituted by hydroxyl, alkoxy comprising from 1 to 6atoms, amino, alkylamino comprising from 1 to 6 atoms, dialkylaminocomprising from 2 to 12 carbon atoms, alkyl comprising from 1 to 12carbon atoms, or halogen groups.

Even more preferably, R₁ and R₂ represent an alkyl group and inparticular a methyl group, and R₃ and R₄ represent hydrogen atoms. Inthis case, the PPE resin is a poly(2,6-dimethyl-1,4-phenylene ether).

Also preferably, n is an integer within a range extending from 3 to 50,more preferably from 5 to 30 and preferably from 6 to 20.

Preferably, the PPE resin is a compound comprising more than 80% byweight, and more preferably still more than 95% by weight ofpolyphenylene units of general formula (I).

Mention may be made, as examples, of poly(2,6-dimethyl-1,4-phenyleneether) and especially Noryl SA 120 from Sabic or Xyron S201 from AsahiKasei.

The PPE resin which is useful for the requirements of the invention ispreferably “compatible” with the vinylaromatic diene elastomer of thecomposition. As defined above, “compatible” is intended to mean thatthis PPE resin does not form particles in the composition, that is tosay that a resin will be referred to as compatible if it gives, in amixture with the vinylaromatic diene elastomer, a composition havingless than 10%, preferably less than 5% and more preferably less than 2%,of its volume in the form of particles greater than 2 micrometres insize. The measurement method, using the TOM, is described above.Alternatively and also preferably, this PPE resin is compatible with thevinylaromatic diene elastomer such that it is capable of increasing theTg of the elastomer; that is to say, it will enable the glass transitiontemperature Tg of a mixture of said vinylaromatic diene elastomer andsaid resin to increase by more than 5° C., preferably by more than 10°C., preferably by more than 12° C. for 25 parts by weight per hundredparts by weight of elastomer (phr) of said resin, compared to the Tg ofsaid vinylaromatic diene elastomer alone.

The content of PPE resin in the composition is preferably within a rangeextending from 1 to 90 phr, more preferably from 2 to 80 phr, morepreferably still from 3 to 60 phr and very preferably from 5 to 60 phr.

II.4. Crosslinking System

The crosslinking system can be a vulcanization system; it is preferablybased on sulphur or sulphur donors and on primary vulcanizationaccelerator (preferably 0.5 to 10.0 phr of primary accelerator).Additional to this vulcanization system are optionally various knownsecondary vulcanization accelerators and/or vulcanization activators,such as zinc oxide (preferably for 0.5 to 10.0 phr), stearic acid orothers. The sulphur is used at a preferred content of between 0.5 and 10phr, more preferably of between 0.5 and 5.0 phr, for example between 0.5and 3.0 phr when the invention is applied to a tyre tread.

Use may be made, as (primary or secondary) accelerator, of any compoundcapable of acting as accelerator of the vulcanization of dieneelastomers in the presence of sulphur, especially accelerators of thethiazole type and their derivatives and accelerators of the thiuram andzinc dithiocarbamate types. These accelerators are more preferablyselected from the group consisting of 2-mercaptobenzothiazole disulphide(abbreviated to “MBTS”), N-cyclohexyl-2-benzothiazolesulphenamide(abbreviated to “CBS”), N, N-dicyclohexyl-2-benzothiazolesulphenamide(abbreviated to “DCBS”), N-(tert-butyl)-2-benzothiazolesulphenamide(abbreviated to “TBBS”), N-(tert-butyl)-2-benzothiazolesulphenimide(abbreviated to “TBSI”), zinc dibenzyldithiocarbamate (abbreviated to“ZBEC”) and the mixtures of these compounds. Preferably, use is made ofa primary accelerator of the sulphenamide type.

II.5. Various Additives

The rubber compositions of the treads in accordance with the inventionalso comprise all or some of the usual additives generally used inelastomer compositions intended for the manufacture of treads, such as,for example, pigments, protection agents, such as antiozone waxes,chemical antiozonants, antioxidants, antifatigue agents, reinforcingresins or plasticizing agents. Preferably, this plasticizing agent is asolid hydrocarbon-based resin other than the resin described above (orplasticizing resin), an extending oil (or plasticizing oil) or a mixtureof the two.

These compositions may also comprise, in addition to the couplingagents, coupling activators, agents for covering the inorganic fillersor more generally processing aids capable, in a known way, by virtue ofan improvement in the dispersion of the filler in the rubber matrix andof a lowering of the viscosity of the compositions, of improving theirability to be processed in the raw state, these agents being, forexample, hydrolysable silanes, such as alkylalkoxysilanes, polyols,polyethers, primary, secondary or tertiary amines, or hydroxylated orhydrolysable polyorganosiloxanes.

II.6. Preparation of the Rubber Compositions

The compositions used in the treads of the invention can be manufacturedin appropriate mixers, using two successive phases of preparation wellknown to those skilled in the art: a first phase of thermomechanicalworking or kneading (“non-productive” phase) at high temperature, up toa maximum temperature of between 110° C. and 190° C., preferably between130° C. and 180° C., followed by a second phase of mechanical working(“productive” phase) to a lower temperature, typically of less than 110°C., for example between 40° C. and 100° C., during which finishing phasethe crosslinking system is incorporated.

The process for preparing such compositions comprises, for example, thefollowing steps:

-   -   incorporating into the elastomers, especially the vinylaromatic        diene elastomer, during a (“non-productive”) first step, the        reinforcing filler, the PPE resin and optional other ingredients        of the composition with the exception of the crosslinking        system, by thermomechanically kneading everything (for example        once or several times) until a maximum temperature of between        110° C. and 190° C. is achieved;    -   cooling the combined mixture to a temperature of less than 100°        C.;    -   subsequently incorporating, during a (“productive”) second step,        a crosslinking system;    -   kneading everything to a maximum temperature of less than 110°        C.

By way of example, the non-productive phase is carried out in a singlethermomechanical step during which, firstly, all the necessary baseconstituents (elastomers, reinforcing filler, PPE resin and others) areintroduced into an appropriate mixer, such as a standard internal mixer,followed secondly, for example after kneading for one to two minutes, bythe other additives, optional additional agents for covering the filleror optional additional processing aids, with the exception of thecrosslinking system. The total duration of kneading in thisnon-productive phase is preferably between 1 and 15 minutes. Aftercooling the mixture thus obtained, the crosslinking system is thenincorporated in an external mixer, such as an open mill, maintained at alow temperature (for example between 40° C. and 100° C.). The combinedmixture is then mixed (productive phase) for a few minutes, for examplebetween 2 and 15 min.

The final composition thus obtained can subsequently be calendered, forexample in the form of a sheet or of a slab, especially for laboratorycharacterization, or else extruded, for example in order to form arubber profiled element used in the manufacture of a tyre.

The invention relates to the tyres and the semi-finished products fortyres described above, rubber articles, both in the raw state (that isto say, before curing) and in the cured state (that is to say, aftercrosslinking or vulcanization).

II.7. Tyre of the Invention

The rubber composition according to the invention may be used indifferent parts of the tyre, in particular in the crown, the carcass,the area of the bead, the area of the sidewall and the tread (includingespecially the underlayer of the tread).

According to a preferred embodiment of the invention, the rubbercomposition described above may be used in the tyre as a stiff elastomerlayer in at least one part of the tyre.

The term elastomer “layer” is understood to mean any three-dimensionalcomponent, made of rubber (or “elastomer”, the two being regarded assynonyms) composition, having any shape and thickness, in particularsheet, strip or other component having any cross section, for examplerectangular or triangular.

First of all, the elastomer layer may be used as tread underlayerpositioned in the crown of the tyre between, on the one hand, the tread,i.e. the portion intended to come into contact with the road duringrunning, and, on the other hand, the belt reinforcing the said crown.The thickness of this elastomer layer is preferably within a rangeextending from 0.5 to 10 mm, especially within a range from 1 to 5 mm.

According to another preferred embodiment of the invention, the rubbercomposition according to the invention may be used to form an elastomerlayer positioned in the region of the area of the bead of the tyre,radially between the carcass ply, the bead wire and the turn-up of thecarcass ply.

Another preferred embodiment of the invention can be the use of thecomposition according to the invention to form an elastomer layerpositioned in the area of the sidewall of the tyre.

Alternatively, the composition of the invention may advantageously beused in the tread of the tyre.

III. EXAMPLES OF THE IMPLEMENTATION OF THE INVENTION III.1. Preparationof the Compositions

The following tests are carried out in the following way: thevinylaromatic diene elastomer, the reinforcing filler and the PPE resin,and also the various other ingredients, with the exception of thevulcanization system, are successively introduced into an internal mixer(final degree of filling: approximately 70% by volume), the initialvessel temperature of which is approximately 60° C. Thermomechanicalworking (non-productive phase) is then carried out in one step, whichlasts in total approximately from 3 to 4 min, until a maximum “dropping”temperature of 180° C. is reached.

The mixture thus obtained is recovered and cooled and then sulphur andan accelerator of sulphenamide type are incorporated on a mixer(homofinisher) at 30° C., everything being mixed (productive phase) foran appropriate time (for example between 5 and 12 min).

The compositions thus obtained are subsequently calendered, either inthe form of slabs (thickness from 2 to 3 mm) or of thin sheets ofrubber, for the measurement of their physical or mechanical properties,or extruded in the form of a profiled element.

III.2. Tests on Rubber Compositions

This test illustrates rubber compositions used in tyre treads. Thesecompositions make it possible to increase the Tg of the mixture comparedto a conventional rubber composition (comprising a conventionalplasticizing resin). For this purpose, rubber compositions were preparedas indicated above.

Control compositions C1, C2 and C3 are compositions which areconventional for those skilled in the art, used to manufacture mixturesfor tyre treads.

The compositions of the invention C4 to C6 contain a thermoplastic resinbased on optionally substituted polyphenylene ether units (abbreviatedto “PPE resin”), as described above replacing the C5/C9-cut plasticizingresin customary for those skilled in the art which is used in controlsC2 and C3. The formulations (in phr or parts by weight per hundred partsof elastomer) and their mechanical properties have been summarized inTables 1 and 2 below.

TABLE 1 Composition C1 C2 C3 C4 C5 C6 C7 C8 SBR (1) 100 100 100 100 100100 100 100 Carbon 60 75 85 75 85 85 75 85 black (2) Plasticizing — 2550 — — — — — resin (3) PPE — — — 25 50 — — — Resin 1 (4) PPE — — — — —50 — — Resin 2 (5) PPE — — — — — — 25 50 Resin 3 (6) ZnO (7) 3 3 3 3 3 33 3 Stearic acid (8) 2 2 2 2 2 2 2 2 6PPD (9) 2 2 2 2 2 2 2 2 Sulphur1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 CBS (10) 2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1(1) SBR with 41% of styrene units and 24% of 1,2-units of the butadienepart (Tg, measured by DSC according to standard ASTM D3418, 1999, of−25° C.); (2) ASTM grade N234 (Cabot); (3) C5/C9 Resin, Escorez 2173from Exxon; (4) PPE Resin 1 Poly(2,6-dimethyl-1,4-phenylene ether):Noryl SA120 from Sabic, M_(n) = 2350 g/mol; (5) PPE Resin 2Poly(2,6-dimethyl-1,4-phenylene ether): Xyron S201 A from Asahi Kasei,M_(n) = 19 000 g/mol; (6) PPE Resin 3 Poly(2,6-dimethyl-1,4-phenyleneether): Noryl SA90 from Sabic, M_(n) = 1800 g/mol; (7) Zinc oxide(industrial grade-Umicore); (8) Stearin (Pristerene 4931 from Uniqema);(9) N-(1,3-Dimethylbutyl)-N-phenyl-para-phenylenediamine: Santoflex6-PPD from Flexsys; (10) N-cyclohexylbenzothiazolesulphenamide(Santocure CBS from Flexsys).

TABLE 2 Composition C1 C2 C3 C4 C5 C6 C7 C8 Tg −17° C. −10.5° C. −6.5°C. −1° C. +8.5° C. −12° C. −2.8° C. +12.7° C. % vol particles >2 μm* <2%<2% <2% <2% <2% >10% <2% <2% *measurement carried out on SBR + PPE resinmixture

It is noted that replacing the customary resin with a PPE resin in thecompositions of the invention C4 and C5 makes it possible to obtain anincrease in the temperature corresponding to maximum G″(T), and hence anincrease in the Tg of the mixture, compared to the respective controlcompositions C2 and C3, which is representative of the greaterplasticizing effect of the PPE resin compared to that of conventionalplasticizing resins. It is also noted that the resin used in compositionC6, having a weight Mn of greater than 6000 g/mol, does not make itpossible to obtain this plasticizing effect.

For the compositions of the invention, by virtue of this greaterplasticizing effect than conventional plasticizing resins, it ispossible to reduce the content of resin used and also to reduce thegreen tack brought about by the plasticizing resins and thus facilitatethe manufacture of mixtures.

Examples 2 and 3

Examples 2 and 3 given below are supplementary illustrations of theinvention, in rubber compositions in which the nature of thevinylaromatic diene elastomer and the nature of the filler vary. Example2, like Example 1, shows compositions in which carbon black is thepredominant filler, whereas Example 3 shows compositions in which silicais the predominant reinforcing filler.

Example 2

In this example the vinylaromatic diene elastomer has a Tg of −48° C.

TABLE 3 Composition C1 C2 C3 C4 C5 C6 C7 C8 SBR (1) 100 100 100 100 100100 100 100 Carbon 60 75 85 75 85 85 75 85 black (2) Plasticizing — 2550 — — — — — resin (3) PPE — — — 25 50 — — — Resin 1 (4) PPE — — — — —50 — — Resin 2 (5) PPE — — — — — — 25 50 Resin 3 (6) ZnO (7) 3 3 3 3 3 33 3 Stearic acid (8) 2 2 2 2 2 2 2 2 6PPD (9) 2 2 2 2 2 2 2 2 Sulphur1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 CBS (10) 2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1(1) SBR with 26.5% of styrene units and 24% of 1,2-units of thebutadiene part (Tg, measured by DSC according to standard ASTM D3418,1999, of −48° C.); (2) ASTM grade N234 (Cabot); (3) C5/C9 Resin, Escorez2173 from Exxon; (4) PPE Resin 1 Poly(2,6-dimethyl-1,4-phenylene ether):Noryl SA120 from Sabic, M_(n) = 2350 g/mol; (5) PPE Resin 2Poly(2,6-dimethyl-1,4-phenylene ether): Xyron S201 A from Asahi Kasei,M_(n) = 19 000 g/mol; (6) PPE Resin 3 Poly(2,6-dimethyl-1,4-phenyleneether): Noryl SA90 from Sabic, M_(n) = 1800 g/mol; (7) Zinc oxide(industrial grade-Umicore); (8) Stearin (Pristerene 4931 from Uniqema);(9) N-(1,3-Dimethylbutyl)-N-phenyl-para-phenylenediamine: Santoflex6-PPD from Flexsys; (10) N-cyclohexylbenzothiazolesulphenamide(Santocure CBS from Flexsys).

TABLE 4 Composition C1 C2 C3 C4 C5 C6 C7 C8 Tg −36.7° C. −28.9° C.−22.3° C. −27.8° C. −22.2° C. −35.5° C. −22.5° C. −17.8° C. % volparticles >2 μm* <2% <2% <2% <2% <2% >10% <2% <2% *measurement carriedout on SBR + PPE resin mixture

Example 3

In this example the vinylaromatic diene elastomer has a Tg of −25° C.

TABLE 5 Composition C1 C2 C3 C4 C5 C6 C7 C8 SBR (1) 100 100 100 100 100100 100 100 Silica (2) 65 85 100 85 100 100 85 100 Plasticizing — 25 50— — — — — resin (3) PPE — — — 25 50 — — — Resin 1 (4) PPE — — — — — 50 —— Resin 2 (5) PPE — — — — — — 25 50 Resin 3 (6) Silane (7) 5 6.5 8 6.5 88 6.5 8 DPG (8) 1 1.4 1.7 1.4 1.7 1.7 1.4 1.7 ZnO (9) 3 3 3 3 3 3 3 3Stearic 2 2 2 2 2 2 2 2 acid (10) 6PPD (11) 2 2 2 2 2 2 2 2 Sulphur 1.41.4 1.4 1.4 1.4 1.4 1.4 1.4 CBS (12) 2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1 (1)SBR with 41% of styrene units and 24% of 1,2-units of the butadiene part(Tg, measured by DSC according to standard ASTM D3418, 1999, of −25°C.); (2) Zeosil1165MP silica from Solvay with BET surface area of 160m²/g; (3) C5/C9 Resin, Escorez 2173 from Exxon; (4) PPE Resin 1Poly(2,6-dimethyl-1,4-phenylene ether): Noryl SA120 from Sabic, M_(n) =2350 g/mol; (5) PPE Resin 2 Poly(2,6-dimethyl-1,4-phenylene ether):Xyron S201 A from Asahi Kasei, M_(n) = 19 000 g/mol; (6) PPE Resin 3Poly(2,6-dimethyl-1,4-phenylene ether): Noryl SA90 from Sabic, M_(n) =1800 g/mol; (7) TESPT coupling agent: SI69 from Evonik; (8)Diphenylguanidine: Perkacit DPG from Flexsys; (9) Zinc oxide (industrialgrade-Umicore); (10) Stearin (Pristerene 4931 from Uniqema); (11)N-(1,3-Dimethylbutyl)-N-phenyl-para-phenylenediamine: Santoflex 6-PPDfrom Flexsys; (12) N-cyclohexylbenzothiazolesulphenamide (Santocure CBSfrom Flexsys).

TABLE 6 Composition C1 C2 C3 C4 C5 C6 C7 C8 Tg −18° C. −12° C. −7.9° C.−5° C. +4.3° C. −14° C. −2.8° C. +8.3° C. % vol particles >2 μm* <2% <2%<2% <2% <2% >10% <2% <2% *measurement carried out on SBR + PPE resinmixture

1.-34. (canceled)
 35. A rubber composition based on: at least onepredominant vinylaromatic diene elastomer; a reinforcing filler; acrosslinking system; and a thermoplastic resin comprising optionallysubstituted polyphenylene ether units, wherein said thermoplastic resinhas a number-average molecular weight Mn of less than 6000 g/mol. 36.The rubber composition according to claim 35, wherein said thermoplasticresin has a number-average molecular weight Mn of less than 3500 g/mol.37. The rubber composition according to claim 36, wherein saidthermoplastic resin has a number-average molecular weight Mn within arange extending from 700 to 2500 g/mol.
 38. The rubber compositionaccording to claim 35, wherein the vinylaromatic diene elastomer has avinylaromatic content of greater than 10%.
 39. The rubber compositionaccording to claim 38, wherein the vinylaromatic diene elastomer has avinylaromatic content of between 15% and 60%.
 40. The rubber compositionaccording to claim 39, wherein the vinylaromatic diene elastomer has avinylaromatic content of preferably between 20% and 50%.
 41. The rubbercomposition according to claim 40, wherein the vinylaromatic dieneelastomer has a vinylaromatic content of between 30% and 50%.
 42. Therubber composition according to claim 41, wherein the vinylaromaticdiene elastomer has a vinylaromatic content of between 35% and 50%. 43.The rubber composition according to claim 35, wherein the vinylaromaticdiene elastomer has a vinylaromatic content of between 10% and 30%, andwherein said thermoplastic resin has a number-average molecular weightMn of less than 2200 g/mol.
 44. The rubber composition according toclaim 43, wherein the vinylaromatic diene elastomer has a vinylaromaticcontent of between 12% and 28%, and wherein said thermoplastic resin hasa number-average molecular weight Mn of less than 2000 g/mol.
 45. Therubber composition according to claim 44, wherein the vinylaromaticdiene elastomer has a vinylaromatic content of between 14% and 20%, andwherein said thermoplactic resin has a number-average molecular weightMn within a range extending from 700 to 2000 g/mol.
 46. The rubbercomposition according to claim 35, wherein the vinylaromatic dieneelastomer is selected from the group consisting of butadiene/styrenecopolymers, isoprene/styrene copolymers and butadiene/isoprene/styrenecopolymers and mixtures thereof.
 47. The rubber composition according toclaim 46, wherein the vinylaromatic diene elastomer is selected from thegroup consisting of butadiene/styrene copolymers and mixtures thereof.48. The rubber composition according to claim 35, wherein the content ofvinylaromatic diene elastomer is within a range extending from 70 to 100phr (parts by weight per hundred parts of elastomer).
 49. The rubbercomposition according to claim 48, wherein the content of vinylaromaticelastomer is within a range extending from 85 to 100 phr.
 50. The rubbercomposition according to claim 35, wherein the thermoplastic resin basedon optionally substituted polyphenylene ether units has a glasstransition temperature Tg, measured by DSC according to standard ASTMD3418, 1999, within a range extending from 0 to 215° C.
 51. The rubbercomposition according to claim 50, wherein the thermoplastic resin basedon optionally substituted polyphenylene ether units has a glasstransition temperature Tg, measured by DSC according to standard ASTMD3418, 1999, within a range extending from 5 to 200° C.
 52. The rubbercomposition according to claim 51, wherein the thermoplastic resin basedon optionally substituted polyphenylene ether units has a glasstransition temperature Tg, measured by DSC according to standard ASTMD3418, 1999, within a range extending from 5 to 185° C.
 53. The rubbercomposition according to claim 35, wherein the thermoplastic resin basedon optionally substituted polyphenylene ether units is a compound whichpredominantly comprises polyphenylene units of general formula (I):

wherein R₁, R₂, R₃ and R₄ represent, independently of one another,identical or different groups selected from the group consisting ofhydrogen, hydroxyl, alkoxy, halogen, amino, alkylamino groups,dialkylamino groups and hydrocarbon-based groups comprising at least 2carbon atoms, optionally interrupted by heteroatoms and optionallysubstituted, wherein R₁ and R₃ or R₂ and R₄ may form, together with thecarbon atoms to which they are attached, one or more rings fused to thebenzene ring of the compound of formula (I), and wherein n is an integerwithin a range extending from 3 to
 300. 54. The rubber compositionaccording to 53, wherein the thermoplastic resin based on optionallysubstituted polyphenylene ether units is a compound predominantlycomprising polyphenylene units of general formula (I) in which R₁, R₂,R₃ and R₄ represent, independently of one another, identical ordifferent groups selected from the group consisting of hydrogen,hydroxyl, alkoxy, halogen, amino, alkylamino groups, dialkylaminogroups, alkyl groups and aryl groups, wherein the alkyl groups arelinear, branched or cyclic alkyl groups, comprising from 1 to 25 carbonatoms, optionally interrupted by heteroatoms selected from nitrogen,oxygen and sulfur and optionally substituted by hydroxyl, alkoxy, amino,alkylamino, dialkylamino or halogen groups, and wherein the aryl groupscomprise from 6 to 18 carbon atoms, optionally substituted by hydroxyl,alkoxy, amino, alkylamino, dialkylamino, alkyl or halogen groups. 55.The rubber composition according to claim 54, wherein the alkyl groupscomprise from 2 to 18 carbon atoms and the aryl groups comprise from 6to 12 carbon atoms.
 56. The rubber composition according to claim 53,wherein the thermoplastic resin based on optionally substitutedpolyphenylene ether units is a compound predominantly comprisingpolyphenylene units of general formula (I), wherein R₁, R₂, R₃ and R₄represent, independently of one another, identical or different groupsselected from the group consisting of hydrogen, hydroxyl, alkoxycomprising from 1 to 6 carbon atoms, halogen, amino, alkylaminocomprising from 1 to 6 carbon atoms, dialkylamino comprising from 2 to12 carbon atoms groups, alkyl groups and aryl groups, wherein the alkylgroups are linear, branched or cyclic alkyl groups, comprising from 1 to12 carbon atoms, optionally interrupted by heteroatoms and optionallysubstituted by hydroxyl, alkoxy comprising from 1 to 6 carbon atoms,amino, alkylamino comprising from 1 to 6 carbon atoms, dialkylaminocomprising from 2 to 12 carbon atoms, or halogen groups, and wherein thearyl groups comprise from 6 to 18 carbon atoms, optionally substitutedby hydroxyl, alkoxy comprising from 1 to 6 atoms, amino, alkylaminocomprising from 1 to 6 atoms, dialkylamino comprising from 2 to 12carbon atoms, alkyl comprising from 1 to 12 carbon atoms, or halogengroups.
 57. The rubber composition according to claim 56, wherein thealkyl groups comprise from 2 to 6 carbon atoms and the aryl groupscomprise from 6 to 12 carbon atoms.
 58. The rubber composition accordingto claim 53, wherein R₁ and R₂ each represent an alkyl group, and R₃ andR₄ each represent a hydrogen atom.
 59. The rubber composition accordingto claim 58, wherein R₁ and R₂ each represent a methyl group.
 60. Therubber composition according to claim 53, wherein the thermoplasticresin based on optionally substituted polyphenylene ether units is acompound which predominantly comprises polyphenylene units of generalformula (I), and wherein n is an integer within a range extending from 3to
 50. 61. The rubber composition according to claim 60, wherein n is aninteger within a range extending from 5 to
 30. 62. The rubbercomposition according to claim 61, wherein n is an integer within arange extending from 6 to
 20. 63. The rubber composition according toclaim 53, wherein the thermoplastic resin based on optionallysubstituted polyphenylene ether units is a compound which comprises morethan 80% by weight of polyphenylene units of general formula (I). 64.The rubber composition according to claim 63, wherein the thermoplasticresin based on optionally substituted polyphenylene ether units is acompound which comprises more than 95% by weight of polyphenylene unitsof general formula (I).
 65. The rubber composition according to claim35, wherein the content of said thermoplastic resin based on optionallysubstituted polyphenylene ether units is within a range extending from 1to 90 phr.
 66. The rubber composition according to claim 65, wherein thecontent of said thermoplastic resin based on optionally substitutedpolyphenylene ether units is within a range extending from 2 to 80 phr.67. The rubber composition according to claim 66, wherein the content ofsaid thermoplastic resin based on optionally substituted polyphenyleneether units is within a range extending from 3 to 60 phr.
 68. The rubbercomposition according to claim 67, wherein the content of saidthermoplastic resin based on optionally substituted polyphenylene etherunits is within a range extending from 5 to 60 phr.
 69. The rubbercomposition according to claim 35, wherein the reinforcing fillercomprises carbon black, silica or a combination thereof.
 70. The rubbercomposition according to claim 35, wherein the reinforcing fillerrepresents between 20 and 200 phr.
 71. The rubber composition accordingto claim 70, wherein the reinforcing filler represents between 30 and160 phr.
 72. The rubber composition according to claim 35, wherein thereinforcing filler predominantly comprises carbon black.
 73. The rubbercomposition according to claim 72, wherein the carbon black representsfrom 60 to 160 phr.
 74. The rubber composition according to claim 73,wherein the carbon black represents from 70 to 150 phr.
 75. The rubbercomposition according to claim 35, wherein the reinforcing fillerpredominantly comprises silica.
 76. The rubber composition according toclaim 75, wherein the silica represents from 60 to 160 phr.
 77. Therubber composition according to claim 76, wherein the silica representsfrom 70 to 150 phr.
 78. A finished or semi-finished rubber articlecomprising a rubber composition according to claim
 35. 79. A tirecomprising a rubber composition according to claim
 35. 80. The tireaccording to claim 79, wherein the rubber composition comprises a tread.